The present invention relates to a three-dimensional data processing apparatus, a three-dimensional data processing method and a three-dimensional data processing program. More particularly, the present invention relates to an apparatus, a method or a program that has capabilities to search for a part similar to a predetermined shape from inputted shape models (CAD models, or mesh models) and is able to change the search scope in terms of size and/or topology.
Conventionally, in the field of CAD (Computer Aided Design) or CG (Computer Graphics), methods have been proposed that automatically searches for a model that is similar to the shape models. For example, in a Japanese Laid-open Patent Application JP-A-2001-117907 (Method and system for comparatively retrieving for polyhedral shapes), a system is disclosed in which a polyhedral shape model (polygon model) is digitized from an axial moment function of a polyhedron to search for a model similar to the polyhedral shape model. As just described, there exist publicly known conventional techniques that search for the polyhedral shapes. However, there exists no technique yet for searching for a partial characteristic shape existing within a polyhedral shape.
As an example, in a three-dimensional CAD for designing industrial products, a scene can be supposed in which a housing of a hard disc recorder for receiving and recording a TV broadcasting program is being designed. The housing is created by applying metal sheet bending processing to an aluminum plate. The housing comprises: a printed board in which an element responsible for signal processing, such as DSP, is wired; a panel that includes a button switch for receiving operations by a user and a liquid crystal display device for performing predetermined display; and a switching power source unit for supplying power. Since these components are delivered by different suppliers, each of the components is mounted to the housing by screws of different sizes.
Now, a scene is supposed in which thread holes need to be redesigned during the creation of a design drawing through the use of CAD. If the number of screws to be used is small, a designer just has to search for all the screws imagined by the designer from data within the CAD to perform predetermined redesigning processing including replacement. However, if the number of the screws is enormous, or if the shape of the housing is complicated, only the processing by man's brain can not handle the matter and thereby errors such as edit omission may more likely occur.
In the conventional CAD systems, data on components having common threaded holes or the like are prepared in a CAD data file or a CAD software. Therefore, when the pointer is placed on the component data, further information corresponding to the common threaded holes that exist in the data becomes available, thus enabling the collective designation of CAD data to be created and edited. However, this method is effective only when the components in the data perfectly match a desired shape. Actually, the method does not work well when the components in the data are just similar to the desired shape. In addition, when transmitting and receiving data between different CAD systems, such as between designers and suppliers, if their data format differs, information on the component data will be lost, disabling the search for similar part shapes. Naturally, since some suppliers cannot imagine the same information on the component data as that imagined by the designer, manual searching of the components will possibly lead to more errors.
While in the above example, threaded holes are described, there are a great number of cases in which parts of similar shape are desired to be retrieved in the three-dimensional CAD. Furthermore, the three-dimensional CAD is not limited to the designing of industrial products. Some three-dimensional CADs are used for the creation of CG or the like such as animations. In addition, the technique for retrieving parts of similar shape is adaptable to computer games or the like, thus the present invention being adaptable to a wide variety of applications.